4RO TCI in 83 XJ

[Axel]

As some of you know ,I'm using a 4RO TCI from a 81 XS in my 83 XJ . It has been mentioned that I may not be accessing an advance feature since the XJ TCI works with a boost sensor actuated by vacuum . I have a XJ TCI to test with as well .
I'm wondering which setup will give me more power on the take off and which will give better gas mileage ?
Any ideas ? It seems to have lots of power now and gets about 40 mpg imperial . This is my first 1100 cc bike and so I dont really have anything to compare it to .

[blue giant]

Hey Alex!

40 mpg is about what I get with my XJ1100. I would think that having the proper TCI would give you the best of both worlds but I know hard hard to has been to locate a reasonably priced TCI.

Paul

[Axel]

tweaking

I got a XJ TCI from a fellow on here for a good price but havent tried it out yet . I'm wondering if the advance gives you more power under acceleration and if I have reached my limit for mileage . I still want to try the low or no resistance caps and maybe more plug gap .I have also used the acetone . I get the best mileage with Shell V-Power ethanol free .

[TopCatGr58]

Hey Axel,

The XJ's TCI should provide the best chance for the best mileage under cruising conditions, and just smoother transitions from cruising into under load/throttle changes. IT won't provide any more power or better accelleration because as I've explained before, the VAC adv. actually RETARDS the very advanced timing that is occuring during cruising/low load rpms back to the more powerful timing setting for the heavy throttle input. The 4RO TCI provides that amount of advance with it's cent. programming, it just doesn't have the extra advance needed for the lean cruising low throttle input. As was stated, 40MPG is very good to begin with, and would be interesting to see if you got anymore with the XJ TCI vs. the 4RO!
T.C.

[Axel]

Again

Hey . Sorry to make you repeat yourself T.C. - Memory is a challenge . I am hoping for a better understanding of the purpose of the advance from this thread .
40 mpg Imperial is of course only 33 mpg U.S. so if I have the chance for better mileage - I am up for it .
Bike seems to run like a bat out of hell with the 4RO TCI so ...I hope I dont lose that with the XJ TCI .

Cheers

[XJOK2PLAY]

Axel,
Your MPG is about what I'm getting...(at it's best) on my '82 XJ.
Mine's pretty much all stock, w/ around 48,000 miles.
I do have some minor carb issues.

(Popping through exhaust @ idle, popping through exhaust on decel, stalling on take off intermittantly... but runs like a heavyweight champ throughout the entire bandwidth otherwise.) Probably float levels... coupled w/ egged jets and worn needles, I'm guessing.

Next week, I'm going to do what a couple of other friends have done to theirs... install a Dynojet kit, needle lowered 1 step, reset the floats, synch...

Their mileage was consistently in the low 30's prior to the Dynojet installation, now both guys' mileage has jumped to low 40's.

Kit cost is $125... but if it gives you a 10 mpg increase, it'll pay for itself quickly... and an extra 50 m p / tank extended range will really be great!

Some here may tell me I'm wasting my $ & time... but after seeing this improvement first hand from 2 friend's bikes... I'm going for it and will post back the results.

Mine averages between 30-32 miles per U.S. gal. at the present.

Best I've ever clocked was 33.

Time will tell... but I think it could just be one of the best mods we could do if it continues to prove out...

[CatatonicBug]

I think the dynajet kit is the way to go. I haven't done it yet myself, but as soon as I can collect the $72 for the pieces, I will just buy the new needles and emulsion tubes from mikesxs. I already have new jets, so no need for those. I've heard that it will improve mileage as well as the studdering on accelleration. A sync and colortune will help your popping on decelleration too.

[Yahman]

Mine averages between 30-32 miles per U.S. gal. at the present.

Best I've ever clocked was 33.

Time will tell... but I think it could just be one of the best mods we could do if it continues to prove out...

That's exactly what I get for mileage, I'll be very interested in what your results are.

Larry

[Axel]

4RO vs 10M TCI

OK - I swapped the 4RO TCI for the 10M TCI (finally!!!) with the slightly different pin config on the pickup coil plug .
First results - Like T.C. said its a smoother transition from cruising mode to power/acceleration mode . That being said there seems to be less grunt off the line ( i even stalled it once) but then the power rolls on exponentially (?) .
It is smoother but seems like its running stronger . The differences are subtle but there .
More to come on the mileage front - I was so stoked to try this that I forgot to eat and had to come home for food after a run to the local Yamaha dealer (80 kms) through some twisties.
I think it passes cars better than before but it may be just the different accel curve .

[Axel]

Yes

Short term mileage test reveals positive results with the 10M XJ TCI. I used to go 125 kms on a half a tank .Now I go 140 kms on half a tank . So 30 kms extra before reserve . Kinda makes me wonder why I didnt do this sooner .

[XJOK2PLAY]

That's exactly what I get for mileage, I'll be very interested in what your results are.

Larry

Cool, Larry... I'll let you know.
Told kit will be in next week. Planning on installing the following weekend.

[XJOK2PLAY]

A sync and colortune will help your popping on decelleration too.

Yeah... Cody & I synched the carbs and reset the floats about 6 months / 3500 miles ago. But no colortune. Not sure he has one of those.
I've done the YICS elimination to mine, also. I hear that needs to be back on to properly colortune.
I was having trouble with being too rich and flooding out some, so we reset the floats. Now I figure we have them to low, and it's too lean. Someone posted the other day that improper float levels (lean) cause the popping.

Hopefully, after next weekend, I won't have those problems anymore!

[Axel]

You sync and color tune with the YICS blanked off . So if you have the Eliminator - all is good

[Axel]

Even an exhaust leak can cause the popping ( backfiring) or 4into 1 pipes I have heard have this challenge.
Color tuning is something I would do before I would ever tear into my carbs (which I have never done- thanks to Seafoam) but the pilot screws can be adjusted in other ways .
Read plugs - adjust accordingly or I think in the tech tips there is a slow idle method of setting pilot screws by ear . This is a good read .

[XJOK2PLAY]

Axel,
I found that thread I mentioned previously... it was member Silent who suggested the YICS be in place when colortuning.

So, for the record... colortune w/ YICS blanked off or eliminator in place?

I know we synched w/ YICS blanked off.

And I agree w/ ya about exhaust leaks causing the popping...

Oddly, mine started doing that once I installed the new J.C.Whitney mufflers.
(But mine are now migged on good.)

My old XJ mufflers were cracked bad, and didn't notice the popping then...

Interesting info, BTW, about the TCI differences and affecting advance curves - performance.